DOI: 10.5194/tc-11-1041-2017
Scopus记录号: 2-s2.0-85019060917
论文题名: A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland
作者: Gray L ; , Burgess D ; , Copland L ; , Dunse T ; , Langley K ; , Moholdt G
刊名: Cryosphere
ISSN: 19940416
出版年: 2017
卷: 11, 期: 3 起始页码: 1041
结束页码: 1058
语种: 英语
英文关键词: ablation
; calibration
; CryoSat
; error correction
; ice thickness
; radar altimetry
; satellite imagery
; snow accumulation
; Canada
; Devon Ice Cap
; Nunavut
英文摘要: We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration-validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the "point-ofclosest- approach" or POCA) and heights derived from delayed waveform returns ("swath" processing). While swathprocessed heights are normally less precise than edited POCA heights, e.g. standard deviations of ∼3 and ∼1.5m respectively for the western Greenland site, the increased coverage possible with swath data complements the POCA data and provides useful information for both system calibration and improving digital elevation models (DEMs). We show that the pre-launch interferometric baseline coupled with an additional roll correction (∼0.0075° ±0.0025°), or equivalent phase correction (∼0.0435±0.0145 radians), provides an improved calibration of the interferometric SARIn mode. We extend the potential use of SARIn data by showing the influence of surface conditions, especially melt, on the return waveforms and that it is possible to detect and measure the height of summer supraglacial lakes in western Greenland. A supraglacial lake can provide a strong radar target in the waveform, stronger than the initial POCA return, if viewed at near-normal incidence. This provides an ideal situation for swath processing and we demonstrate a height precision of ∼0.5m for two lake sites, one in the accumulation zone and one in the ablation zone, which were measured every year from 2010 or 2011 to 2016. Each year the lake in the ablation zone was viewed in June by ascending passes and then 5.5 days later by descending passes, which allows an approximate estimate of the filling rate. The results suggest that CryoSat waveform data and measurements of supraglacial lake height change could complement the use of optical satellite imagery and be helpful as proxy indicators for surface melt around Greenland. © Author(s) 2017. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75563
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, ON, Canada; Geological Survey of Canada, Natural Resources Canada, Ottawa, ON, Canada; Department of Geosciences, University of Oslo, Oslo, Norway; Asiaq, Greenland Survey, Nuuk, Greenland; Norwegian Polar Institute, Tromso, Norway
Recommended Citation:
Gray L,, Burgess D,, Copland L,et al. A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland[J]. Cryosphere,2017-01-01,11(3)